318 Transactions. — Zoology. 



cavities (six in number), the outer surface being thrown up 

 into corresponding folds (fig. 7, en.). The peripharyngeal 

 band is very distinct, and is seen in fig. 7 as yli.io. (pharynx- 

 wall). It is faintly visible in the young zooid (fig. 6). 



The dorsal lamina is represented by a series of long 

 languets (fig. 6, d.l.) arising from the transverse vessels of the 

 branchial sac. 



A small nerve ganglion (fig. 7, n.) and large neural gland 

 (fig. 7, n.g) are found opposite the peripharyngeal band on 

 the dorsal surface. 



The alimentary canal exhibits a return to the type found 

 in L. niveum. Indeed, the only difference of moment is the 

 absence of the pyloric dilatation met with in the former species. 

 The oesophageal curve of the rectum is frequently displaced, 

 being forced downwards through want of room, as shown in 

 fig. 6. The region above the oesophageal constriction shows 

 very clearly the rectum and oesophagus lying side by side 

 (fig. 1, r. and m.). As in all former cases, the lower dilated 

 part of the rectum is distinctly glandular, being more mem- 

 branous above. The atrial pore is plain. 



The testis is a single mass lying near the intestine (fig. 

 1, i^.), and has the vas deferens coiled nine times around it. 

 No ova and no embryos were met with. 



Family (doubtful). 

 Genus Polysynceaton (new). 

 Polysyncraton paradoxum, n. sp. Plate XXVIII. 



A single colony of considerable extent was obtained in July. 

 It was placed at once in spirit, in which it appears to be 

 greyish- white. I have no definite recollection of its natural 

 colour, but imagine it to be white. 



The corm is a thin incrusting mass, varying from l'2mm. 

 to 3mm. in thickness, and is soft to the touch, tearing very 

 easily. The surface appears more homogeneous than in the 

 Leptoclinids examined, but slight traces of the zooids are 

 visible in the form of darker spots. The zooids are arranged 

 very irregularly, but much closer than is usual (see fig. 2). 



The branchial pores are small, and are bwried beneath the 

 surface, so that it is almost impossible to distinguish them. 

 The edges of the branchial siphon are faintly six-lobed. 



No common cloacal openings were discovered. 



Spicules are present throughout the colony ; they are of 

 fairly large size and distinctive form (fig. 3). The rays are 

 very numerous, extremely short, and rounded at the points. 

 Generally three or four circles of such rays are visible, gra- 

 dually increasing in diameter from the centre of the spicule to 

 its outer margin. This would indicate extreme regularity in 

 the arrangement of the rays, as the spicule presents the same 



